Ok, tonight I towed the project car home with my mate. It's now on my drive.
The engine is definately siezed. We're not going to mess - we have a working engine in the other Meega, so it's going to be a direct replacement.
We can borrow an engine crane locally, so the plan is to:
A) Remove the engine from the project car, take off any bits we want (including the cylinder head), and then dump what's left.
B) Remove the engine from the donor car, do any little jobs such as cleaning the breather tube while it's easily accessible, etc, and hoist it into the project car.
C) Reconnect all of the ancilliaries, hoses and connectors etc, fill up the coolant system, and uncle Bob's your auntie - one sweet running Omega.
Then - scrap the engineless old donor car, to make way for the project after that.
A guy I know has just bought a new Elite, and we've done a deal whereas I'm going to take his old CDX V6 omega off his hands.
Another suggestion was to steal the V6 lump out of it and put it in the 2.0 project car, but that's probably not going to happen!!